Heat-transfer fluid for a centrifugal compressor

ABSTRACT

A process for cooling or heating a fluid or a body by a vapor compression circuit having a centrifugal compressor and containing a heat transfer fluid, the heat-transfer fluid including at least two of 2,3,3,3-tetrafluoropropene, 1,3,3,3-tetrafluoropropene, 1,1,1,2-tetrafluoroethane, 1,1-difluoroethane and 3,3,3-trifluoropropene, wherein: the ratio of the Mach number of the centrifugal compressor to the Mach number when the centrifugal compressor has, under the same operating conditions, the heat-transfer fluid is replaced with 1,1,1,2-tetrafluoroethane is at least 0.97 and at most 1.03; the compression ratio of the centrifugal compressor is less than or equal to the compression ratio when the centrifugal compressor has, under the same operating conditions, the heat-transfer fluid is replaced with 1,1,1,2-tetrafluoroethane. Also, equipment suitable for implementing this cooling or heating process, and also to a process for converting existing equipment.

FIELD OF THE INVENTION

The present invention relates to heat transfer fluids suitable for use in vapor compression systems comprising a centrifugal compressor, in particular as a replacement for 1,1,1,2-tetrafluoroethane (HFC-134a).

TECHNICAL BACKGROUND

Fluids based on fluorocarbon compounds are widely used in many industrial devices, in particular air conditioning, heat pump or refrigeration devices. These devices have in common the fact that they are based on a thermodynamic cycle comprising the vaporization of the fluid at low pressure (in which the fluid absorbs heat); the compression of the vaporized fluid to a high pressure; the condensation of the vaporized fluid to liquid at high pressure (in which the fluid releases heat); and the expansion of the fluid in order to complete the cycle.

The compression step is carried out using a compressor, which may be, in particular, a centrifugal compressor.

The choice of a heat transfer fluid (which may be a pure compound or a mixture of compounds) is dictated, on the one hand, by the thermodynamic properties of the fluid and, on the other hand, by additional constraints, and in particular environmental constraints.

It is in this way that chlorinated compounds (chlorofluorocarbons and hydrochlorofluorocarbons) have the disadvantage of damaging the ozone layer. Henceforth, generally non-chlorinated compounds such as hydrofluorocarbons are therefore preferred to them.

In particular, many air conditioning systems currently operate with HFC-134a as heat transfer fluid. However, HFC-134a has a global warming potential (GWP) which is too high. It is therefore desirable to replace HFC-134a with another heat transfer fluid having a lower GWP.

However, any modification of the heat transfer fluid may pose problems in adapting the vapor compression cycle system. In particular, when the cycle uses a centrifugal compressor, the replacement of the heat transfer fluid may require a change of the centrifugal compressor itself or at the very least a modification of the operating parameters of the compressor liable to degrade the efficiency of the system or to accelerate wear phenomena.

Documents WO 97/17414 and U.S. Pat. No. 6,991,743 propose the replacement of dichlorodifluoromethane (CFC-12) with compositions comprising HFC-134a in cycles comprising a centrifugal compressor. The choice of substitute compositions is mainly made as a function of the molecular weight. However, the molecular weight is not in fact sufficiently predictive of the behavior of the various heat transfer fluids.

Document U.S. Pat. No. 5,076,064 proposes the replacement of trichlorofluoromethane (CFC-11) with compositions comprising, in particular, 1,1-dichloro-2,2,2-trifluoroethane (CFC-123) in cycles comprising a centrifugal compressor. The choice of the substitute compositions is mainly made as a function of the Mach number.

Documents WO 2005/108522 and WO 2007/126414 disclose mixtures of fluoroolefins and of other heat transfer compounds as heat transfer fluids. However, these documents do not identify any composition specifically suitable for a vapor compression system comprising a centrifugal compressor.

Document WO 2007/053697 also describes compositions based on fluoroolefins intended to be used as heat transfer fluids. Example 7 describes compounds suitable for replacing 1,2,2-trichlorofluoroethane (CFC-113) in cycles provided with a centrifugal compressor. The choice of the compounds is based on a calculation of theoretical rotational speed of the blades of the compressor. The approximations used in this calculation are however reserved for relatively heavy fluids.

Document WO 2009/018117 describes mixtures of fluoroolefins and of other heat transfer compounds as heat transfer fluids, especially as a replacement for HFC-134a. However, this document does not identify any composition specifically suitable for a vapor compression system comprising a centrifugal compressor.

Document WO 2009/151669 describes various heat transfer compositions based on specific lubricants and fluoroolefins.

None of the documents of the prior art proposes a heat transfer fluid as a replacement for HFC-134a in a vapor compression system comprising a centrifugal compressor, which both has a GWP below that of HFC-134a and guarantees the maintenance or even an improvement of the performances of the centrifugal compressor relative to HFC-134a.

There is therefore a real need to develop such a heat transfer fluid.

SUMMARY OF THE INVENTION

The invention firstly relates to a process for cooling or heating a fluid or a body by means of a vapor compression circuit comprising a centrifugal compressor and containing a heat transfer fluid, the heat transfer fluid comprising at least two compounds chosen from 2,3,3,3-tetrafluoropropene, 1,3,3,3-tetrafluoropropene, 1,1,1,2-tetrafluoroethane, 1,1-difluoroethane and 3,3,3-trifluoropropene, wherein:

-   -   the ratio of the Mach number of the centrifugal compressor to         the Mach number that the centrifugal compressor has, under the         same operating conditions, when the heat transfer fluid is         replaced by 1,1,1,2-tetrafluoroethane in the vapor compression         circuit, is greater than or equal to 0.97 and less than or equal         to 1.03;     -   the compression ratio of the centrifugal compressor is less than         or equal to the compression ratio that the centrifugal         compressor has, under the same operating conditions, when the         heat transfer fluid is replaced by 1,1,1,2-tetrafluoroethane in         the vapor compression circuit.

The invention furthermore relates to an installation for cooling or heating a fluid or a body, for the implementation of the above process, comprising a vapor compression circuit comprising a centrifugal compressor and containing a heat transfer fluid, the heat transfer fluid comprising at least two compounds chosen from 2,3,3,3-tetrafluoropropene, 1,3,3,3-tetrafluoropropene, 1,1,1,2-tetrafluoroethane, 1,1-difluoroethane and 3,3,3-trifluoropropene (and mixtures thereof), wherein:

-   -   the ratio of the Mach number of the centrifugal compressor to         the Mach number that the centrifugal compressor has, under the         same operating conditions, when the heat transfer fluid is         replaced by 1,1,1,2-tetrafluoroethane in the vapor compression         circuit, is greater than or equal to 0.97 and less than or equal         to 1.03;     -   the compression ratio of the centrifugal compressor is less than         or equal to the compression ratio that the centrifugal         compressor has, under the same operating conditions, when the         heat transfer fluid is replaced by 1,1,1,2-tetrafluoroethane in         the vapor compression circuit.

The invention furthermore relates to a process for converting a vapor compression circuit, which consists in replacing an existing heat transfer fluid with the above heat transfer fluid. This process comprises:

-   -   the provision of an initial vapor compression circuit comprising         a centrifugal compressor and containing         1,1,1,2-tetrafluoroethane as heat transfer fluid; and     -   the replacement of the 1,1,1,2-tetrafluoroethane with a         substitute heat transfer fluid in order to provide a final vapor         compression circuit;         wherein the substitute heat transfer fluid comprises at least         two compounds chosen from 2,3,3,3-tetrafluoropropene,         1,3,3,3-tetrafluoropropene, 1,1,1,2-tetrafluoroethane,         1,1-difluoroethane and 3,3,3-trifluoropropene (and mixtures         thereof), and wherein:     -   the ratio of the Mach number of the centrifugal compressor in         the final vapor compression circuit to the Mach number of the         centrifugal compressor in the initial vapor compression circuit,         under the same operating conditions, is greater than or equal to         0.97 and less than or equal to 1.03; and     -   the compression ratio of the centrifugal compressor in the final         vapor compression circuit is less than or equal to the         compression ratio of the centrifugal compressor in the initial         vapor compression circuit, under the same operating conditions.

According to one embodiment of the cooling or heating process, of the cooling or heating installation and of the process for converting a vapor compression circuit above, the heat transfer fluid (where appropriate the substitute heat transfer fluid) comprises, preferably consists of, a mixture:

-   -   of 2,3,3,3-tetrafluoropropene and of 1,1,1,2-tetrafluoroethane;         or     -   of 2,3,3,3-tetrafluoropropene and of 1,1-difluoroethane; or     -   of 2,3,3,3-tetrafluoropropene and of 3,3,3-trifluoropropene; or     -   of 1,3,3,3-tetrafluoropropene and of 3,3,3-trifluoropropene; or     -   of 1,1,1,2-tetrafluoroethane and of 3,3,3-trifluoropropene; or     -   of 2,3,3,3-tetrafluoropropene, of 1,3,3,3-tetrafluoropropene and         of 1,1-difluoroethane;     -   of 2,3,3,3-tetrafluoropropene, of 1,1,1,2-tetrafluoroethane and         of 1,1-difluoroethane; or     -   of 2,3,3,3-tetrafluoropropene, of 1,1,1,2-tetrafluoroethane and         of 3,3,3-trifluoropropene; or     -   of 2,3,3,3-tetrafluoropropene, of 1,1-difluoroethane and of         3,3,3-trifluoropropene; or     -   of 1,3,3,3-tetrafluoropropene, of 1,1,1,2-tetrafluoroethane and         of 1,1-difluoroethane; or     -   of 1,3,3,3-tetrafluoropropene, of 1,1-difluoroethane and of         3,3,3-trifluoropropene.

According to another embodiment of the cooling or heating process and of the cooling or heating installation above, the vapor compression circuit comprises an evaporator and a condenser, and:

-   -   the difference between the pressure at the condenser and the         pressure at the evaporator is less than or equal to the         difference between the pressure at the condenser and the         pressure at the evaporator which is obtained, under the same         operating conditions, when the heat transfer fluid is replaced         by 1,1,1,2-tetrafluoroethane in the vapor compression circuit.

According to one embodiment of the process for converting a vapor compression circuit above, the (initial or final) vapor compression circuit comprises an evaporator and a condenser, and:

-   -   the difference between the pressure at the condenser and the         pressure at the evaporator in the final vapor compression         circuit is less than or equal to the difference between the         pressure at the condenser and the pressure at the evaporator in         the initial vapor compression circuit, under the same operating         conditions.

According to a first variant of the cooling or heating process or of the cooling or heating installation above, the centrifugal compressor is provided with rotational speed adaptation means, and:

-   -   the rotational speed of the centrifugal compressor is less than         or equal to the rotational speed that the centrifugal compressor         has, under the same operating conditions, when the heat transfer         fluid is replaced by 1,1,1,2-tetrafluoroethane in the vapor         compression circuit.

According to a first variant of the process for converting a vapor compression circuit above, the centrifugal compressor is provided with rotational speed adaptation means, and:

-   -   the rotational speed of the centrifugal compressor in the final         vapor compression circuit is adjusted to a value less than or         equal to the rotational speed of the centrifugal compressor in         the initial vapor compression circuit, under the same operating         conditions.

According to the first variant of the above processes and installation (variable speed variant), the heat transfer fluid preferably comprises:

-   -   from 2% to 50% of 2,3,3,3-tetrafluoropropene and from 50% to 98%         of 1,1,1,2-tetrafluoroethane, preferably from 5% to 40% of         2,3,3,3-tetrafluoropropene and from 60% to 95% of         1,1,1,2-tetrafluoroethane, and more particularly preferably from         5% to 30% of 2,3,3,3-tetrafluoropropene and from 70% to 95% of         1,1,1,2-tetrafluoroethane; or     -   from 50% to 95% of 2,3,3,3-tetrafluoropropene and from 5% to 50%         of 1,1-difluoroethane, preferably from 60% to 95% of         2,3,3,3-tetrafluoropropene and from 5% to 40% of         1,1-difluoroethane, and more particularly preferably from 85% to         90% of 2,3,3,3-tetrafluoropropene and from 10% to 15% of         1,1-difluoroethane; or     -   from 10% to 70% of 2,3,3,3-tetrafluoropropene and from 30% to         90% of 3,3,3-trifluoropropene, preferably from 20% to 60% of         2,3,3,3-tetrafluoropropene and from 40% to 80% of         3,3,3-trifluoropropene, and more particularly preferably from         40% to 50% of 2,3,3,3-tetrafluoropropene and from 50% to 60% of         3,3,3-trifluoropropene; or     -   from 20% to 70% of 1,3,3,3-tetrafluoropropene and from 30% to         80% of 3,3,3-trifluoropropene, preferably from 30% to 60% of         1,3,3,3-tetrafluoropropene and from 40% to 70% of         3,3,3-trifluoropropene, and more particularly preferably from         30% to 50% of 1,3,3,3-tetrafluoropropene and from 50% to 70% of         3,3,3-trifluoropropene; or     -   from 10% to 70% of 1,1,1,2-tetrafluoroethane and from 30% to 90%         of 3,3,3-trifluoropropene, preferably from 20% to 60% of         1,1,1,2-tetrafluoroethane and from 40% to 80% of         3,3,3-trifluoropropene, and more particularly preferably from         35% to 50% of 1,1,1,2-tetrafluoroethane and from 55% to 65% of         3,3,3-trifluoropropene; or     -   from 10% to 90% of 2,3,3,3-tetrafluoropropene, from 5% to 70% of         1,3,3,3-tetrafluoropropene and from 5% to 30% of         1,1-difluoroethane, preferably from 20% to 85% of         2,3,3,3-tetrafluoropropene, from 5% to 60% of         1,3,3,3-tetrafluoropropene and from 10% to 20% of         1,1-difluoroethane, and more particularly preferably from 30% to         85% of 2,3,3,3-tetrafluoropropene, from 5% to 50% of         1,3,3,3-tetrafluoropropene and from 10% to 15% of         1,1-difluoroethane; or     -   from 10% to 93% of 2,3,3,3-tetrafluoropropene, from 5% to 80% of         1,1,1,2-tetrafluoroethane and from 2% to 50% of         1,1-difluoroethane, preferably from 13% to 93% of         2,3,3,3-tetrafluoropropene, from 5% to 60% of         1,1,1,2-tetrafluoroethane and from 2% to 30% of         1,1-difluoroethane, and more particularly preferably from 25% to         92% of 2,3,3,3-tetrafluoropropene, from 5% to 60% of         1,1,1,2-tetrafluoroethane and from 3% to 15% of         1,1-difluoroethane; or     -   from 5% to 90% of 2,3,3,3-tetrafluoropropene, from 5% to 60% of         1,1,1,2-tetrafluoroethane and from 5% to 70% of         3,3,3-trifluoropropene, preferably from 10% to 85% of         2,3,3,3-tetrafluoropropene, from 5% to 60% of         1,1,1,2-tetrafluoroethane and from 10% to 70% of         3,3,3-trifluoropropene, and more particularly preferably from         10% to 60% of 2,3,3,3-tetrafluoropropene, from 5% to 50% of         1,1,1,2-tetrafluoroethane and from 20% to 60% of         3,3,3-trifluoropropene; or     -   from 10% to 89% of 2,3,3,3-tetrafluoropropene, from 3% to 20% of         1,1-difluoroethane and from 8% to 70% of 3,3,3-trifluoropropene,         preferably from 35% to 89% of 2,3,3,3-tetrafluoropropene, from         3% to 15% of 1,1-difluoroethane and from 8% to 50% of         3,3,3-trifluoropropene, and more particularly preferably from         50% to 85% of 2,3,3,3-tetrafluoropropene, from 5% to 10% of         1,1-difluoroethane and from 10% to 40% of         3,3,3-trifluoropropene; or     -   from 10% to 60% of 1,3,3,3-tetrafluoropropene, from 20% to 87%         of 1,1,1,2-tetrafluoroethane and from 3% to 20% of         1,1-difluoroethane, preferably from 10% to 40% of         1,3,3,3-tetrafluoropropene, from 45% to 87% of         1,1,1,2-tetrafluoroethane and from 3% to 15% of         1,1-difluoroethane, and more particularly preferably from 10% to         30% of 1,3,3,3-tetrafluoropropene, from 60% to 85% of         1,1,1,2-tetrafluoroethane and from 5% to 10% of         1,1-difluoroethane; or     -   from 25% to 82% of 1,3,3,3-tetrafluoropropene, from 3% to 15% of         1,1-difluoroethane and from 15% to 60% of         3,3,3-trifluoropropene, preferably from 35% to 82% of         1,3,3,3-tetrafluoropropene, from 3% to 15% of 1,1-difluoroethane         and from 15% to 50% of 3,3,3-trifluoropropene, and more         particularly preferably from 40% to 75% of         1,3,3,3-tetrafluoropropene, from 5% to 10% of 1,1-difluoroethane         and from 20% to 50% of 3,3,3-trifluoropropene.

According to a second variant of the above cooling or heating process, cooling or heating installation and process for converting a vapor compression circuit, the centrifugal compressor is devoid of rotational speed adaptation means.

According to this second variant of the above processes and installation (constant speed variant), the heat transfer fluid preferably comprises:

-   -   from 2% to 50% of 2,3,3,3-tetrafluoropropene and from 50% to 98%         of 1,1,1,2-tetrafluoroethane, preferably from 2% to 30% of         2,3,3,3-tetrafluoropropene and from 70% to 98% of         1,1,1,2-tetrafluoroethane, and more particularly preferably from         5% to 15% of 2,3,3,3-tetrafluoropropene and from 85% to 95% of         1,1,1,2-tetrafluoroethane; or     -   from 50% to 90% of 2,3,3,3-tetrafluoropropene and from 10% to         50% of 1,1-difluoroethane, preferably from 60% to 90% of         2,3,3,3-tetrafluoropropene and from 10% to 40% of         1,1-difluoroethane, and more particularly preferably from 70% to         80% of 2,3,3,3-tetrafluoropropene and from 20% to 30% of         1,1-difluoroethane; or     -   from 10% to 40% of 2,3,3,3-tetrafluoropropene and from 60% to         90% of 3,3,3-trifluoropropene, preferably from 10% to 30% of         2,3,3,3-tetrafluoropropene and from 70% to 90% of         3,3,3-trifluoropropene, and more particularly preferably from         10% to 20% of 2,3,3,3-tetrafluoropropene and from 80% to 90% of         3,3,3-trifluoropropene; or     -   from 20% to 70% of 1,3,3,3-tetrafluoropropene and from 30% to         80% of 3,3,3-trifluoropropene, preferably from 20% to 60% of         1,3,3,3-tetrafluoropropene and from 40% to 70% of         3,3,3-trifluoropropene, and more particularly preferably from         30% to 50% of 1,3,3,3-tetrafluoropropene and from 50% to 70% of         3,3,3-trifluoropropene; or     -   from 10% to 70% of 1,1,1,2-tetrafluoroethane and from 30% to 90%         of 3,3,3-trifluoropropene, preferably from 20% to 60% of         1,1,1,2-tetrafluoroethane and from 40% to 80% of         3,3,3-trifluoropropene, and more particularly preferably from         35% to 50% of 1,1,1,2-tetrafluoroethane and from 50% to 65% of         3,3,3-trifluoropropene; or     -   from 15% to 85% of 2,3,3,3-tetrafluoropropene, from 5% to 60% of         1,3,3,3-tetrafluoropropene and from 5% to 30% of         1,1-difluoroethane, preferably from 20% to 85% of         2,3,3,3-tetrafluoropropene, from 5% to 50% of         1,3,3,3-tetrafluoropropene and from 10% to 30% of         1,1-difluoroethane, and more particularly preferably from 35% to         80% of 2,3,3,3-tetrafluoropropene, from 5% to 40% of         1,3,3,3-tetrafluoropropene and from 15% to 25% of         1,1-difluoroethane; or     -   from 18% to 93% of 2,3,3,3-tetrafluoropropene, from 5% to 80% of         1,1,1,2-tetrafluoroethane and from 2% to 50% of         1,1-difluoroethane, preferably from 20% to 93% of         2,3,3,3-tetrafluoropropene, from 5% to 60% of         1,1,1,2-tetrafluoroethane and from 2% to 30% of         1,1-difluoroethane, and more particularly preferably from 30% to         88% of 2,3,3,3-tetrafluoropropene, from 5% to 60% of         1,1,1,2-tetrafluoroethane and from 7% to 20% of         1,1-difluoroethane; or     -   from 10% to 80% of 2,3,3,3-tetrafluoropropene, from 5% to 60% of         1,1,1,2-tetrafluoroethane and from 15% to 80% of         3,3,3-trifluoropropene, preferably from 16% to 75% of         2,3,3,3-tetrafluoropropene, from 5% to 60% of         1,1,1,2-tetrafluoroethane and from 20% to 80% of         3,3,3-trifluoropropene, and more particularly preferably from         10% to 65% of 2,3,3,3-tetrafluoropropene, from 5% to 50% of         1,1,1,2-tetrafluoroethane and from 30% to 80% of         3,3,3-trifluoropropene; or     -   from 10% to 78% of 2,3,3,3-tetrafluoropropene, from 3% to 15% of         1,1-difluoroethane and from 20% to 70% of         3,3,3-trifluoropropene, preferably from 15% to 67% of         2,3,3,3-tetrafluoropropene, from 3% to 10% of 1,1-difluoroethane         and from 30% to 70% of 3,3,3-trifluoropropene, and more         particularly preferably from 21% to 57% of         2,3,3,3-tetrafluoropropene, from 3% to 9% of 1,1-difluoroethane         and from 40% to 70% of 3,3,3-trifluoropropene; or     -   from 15% to 60% of 1,3,3,3-tetrafluoropropene, from 20% to 82%         of 1,1,1,2-tetrafluoroethane and from 3% to 20% of         1,1-difluoroethane, preferably from 15% to 50% of         1,3,3,3-tetrafluoropropene, from 35% to 82% of         1,1,1,2-tetrafluoroethane and from 3% to 15% of         1,1-difluoroethane, and more particularly preferably from 20% to         30% of 1,3,3,3-tetrafluoropropene, from 60% to 75% of         1,1,1,2-tetrafluoroethane and from 5% to 10% of         1,1-difluoroethane; or     -   from 35% to 77% of 1,3,3,3-tetrafluoropropene, from 3% to 15% of         1,1-difluoroethane and from 20% to 50% of         3,3,3-trifluoropropene, preferably from 35% to 72% of         1,3,3,3-tetrafluoropropene, from 3% to 15% of 1,1-difluoroethane         and from 25% to 50% of 3,3,3-trifluoropropene, and more         particularly preferably from 40% to 66% of         1,3,3,3-tetrafluoropropene, from 4% to 10% of 1,1-difluoroethane         and from 30% to 50% of 3,3,3-trifluoropropene.

One subject of the invention is more particularly:

-   -   a process for cooling or heating a fluid or a body by means of a         vapor compression circuit comprising a centrifugal compressor         and containing a heat transfer fluid;     -   an installation for cooling or heating a fluid or a body         comprising a vapor compression circuit comprising a centrifugal         compressor and containing a heat transfer fluid; and     -   a process for converting a vapor compression circuit comprising         the provision of an initial vapor compression circuit comprising         a centrifugal compressor and containing         1,1,1,2-tetrafluoroethane as heat transfer fluid, and the         replacement of the 1,1,1,2-tetrafluoroethane with a substitute         heat transfer fluid in order to provide a final vapor         compression circuit;         in which the heat transfer fluid (that is to say the substitute         heat transfer fluid in the case of the conversion process)         comprises, and preferably consists of:     -   from 2% to 50% of 2,3,3,3-tetrafluoropropene, and from 50% to         98% of 1,1,1,2-tetrafluoroethane; or     -   from 50% to 95% of 2,3,3,3-tetrafluoropropene and from 5% to 50%         of 1,1-difluoroethane; or     -   from 10% to 70% of 2,3,3,3-tetrafluoropropene and from 30% to         90% of 3,3,3-trifluoropropene; or     -   from 20% to 70% of 1,3,3,3-tetrafluoropropene and from 30% to         80% of 3,3,3-trifluoropropene; or     -   from 10% to 70% of 1,1,1,2-tetrafluoroethane and from 30% to 90%         of 3,3,3-trifluoropropene; or     -   from 10% to 90% of 2,3,3,3-tetrafluoropropene, from 5% to 70% of         1,3,3,3-tetrafluoropropene and from 5% to 30% of         1,1-difluoroethane; or     -   from 10% to 93% of 2,3,3,3-tetrafluoropropene, from 5% to 80% of         1,1,1,2-tetrafluoroethane and from 2% to 50% of         1,1-difluoroethane; or     -   from 5% to 90% of 2,3,3,3-tetrafluoropropene, from 5% to 60% of         1,1,1,2-tetrafluoroethane and from 5% to 80% of         3,3,3-trifluoropropene; or     -   from 10% to 89% of 2,3,3,3-tetrafluoropropene, from 3% to 20% of         1,1-difluoroethane and from 8% to 70% of 3,3,3-trifluoropropene;         or     -   from 10% to 60% of 1,3,3,3-tetrafluoropropene, from 20% to 87%         of 1,1,1,2-tetrafluoroethane and from 3% to 20% of         1,1-difluoroethane; or     -   from 25% to 82% of 1,3,3,3-tetrafluoropropene, from 3% to 15% of         1,1-difluoroethane and from 15% to 60% of         3,3,3-trifluoropropene.

According to one embodiment of this more particular invention, the heat transfer fluid comprises:

-   -   from 2% to 30% of 2,3,3,3-tetrafluoropropene, and from 70% to         98% of 1,1,1,2-tetrafluoroethane, preferably from 5% to 15% of         2,3,3,3-tetrafluoropropene and from 85% to 95% of         1,1,1,2-tetrafluoroethane; or     -   from 5% to 40% of 2,3,3,3-tetrafluoropropene and from 60% to 95%         of 1,1,1,2-tetrafluoroethane preferably from 5% to 30% of         2,3,3,3-tetrafluoropropene and from 70% to 95% of         1,1,1,2-tetrafluoroethane; or     -   from 60% to 90% of 2,3,3,3-tetrafluoropropene and from 10% to         40% of 1,1-difluoroethane, preferably from 70% to 80% of         2,3,3,3-tetrafluoropropene and from 20% to 30% of         1,1-difluoroethane; or     -   from 60% to 95% of 2,3,3,3-tetrafluoropropene and from 5% to 40%         of 1,1-difluoroethane, preferably from 85% to 90% of         2,3,3,3-tetrafluoropropene and from 10% to 15% of         1,1-difluoroethane; or     -   from 10% to 30% of 2,3,3,3-tetrafluoropropene and from 70% to         90% of 3,3,3-trifluoropropene, preferably from 10% to 20% of         2,3,3,3-tetrafluoropropene and from 80% to 90% of         3,3,3-trifluoropropene; or     -   from 20% to 60% of 2,3,3,3-tetrafluoropropene and from 40% to         80% of 3,3,3-trifluoropropene, preferably from 40% to 50% of         2,3,3,3-tetrafluoropropene and from 50% to 60% of         3,3,3-trifluoropropene; or     -   from 30% to 60% of 1,3,3,3-tetrafluoropropene and from 40% to         70% of 3,3,3-trifluoropropene, preferably from 30% to 50% of         1,3,3,3-tetrafluoropropene and from 50% to 70% of         3,3,3-trifluoropropene; or     -   from 20% to 60% of 1,1,1,2-tetrafluoroethane and from 40% to 80%         of 3,3,3-trifluoropropene, preferably from 35% to 50% of         1,1,1,2-tetrafluoroethane and from 50% to 65% of         3,3,3-trifluoropropene; or     -   from 20% to 85% of 2,3,3,3-tetrafluoropropene, from 5% to 50% of         1,3,3,3-tetrafluoropropene and from 10% to 30% of         1,1-difluoroethane, preferably from 35% to 80% of         2,3,3,3-tetrafluoropropene, from 5% to 40% of         1,3,3,3-tetrafluoropropene and from 15% to 25% of         1,1-difluoroethane; or     -   from 20% to 85% of 2,3,3,3-tetrafluoropropene, from 5% to 60% of         1,3,3,3-tetrafluoropropene and from 10% to 20% of         1,1-difluoroethane, preferably from 30% to 85% of         2,3,3,3-tetrafluoropropene, from 5% to 50% of         1,3,3,3,-tetrafluoropropene and from 10% to 15% of         1,1-difluoroethane; or     -   from 20% to 93% of 2,3,3,3-tetrafluoropropene, from 5% to 60% of         1,1,1,2-tetrafluoroethane and from 2% to 30% of         1,1-difluoroethane, preferably from 30% to 88% of         2,3,3,3-tetrafluoropropene, from 5% to 60% of         1,1,1,2-tetrafluoroethane and from 7% to 20% of         1,1-difluoroethane; or     -   from 13% to 93% of 2,3,3,3-tetrafluoropropene, from 5% to 60% of         1,1,1,2-tetrafluoroethane and from 2% to 30% of         1,1-difluoroethane, preferably from 25% to 92% of         2,3,3,3-tetrafluoropropene, from 5% to 60% of         1,1,1,2-tetrafluoroethane and from 3% to 15% of         1,1-difluoroethane; or     -   from 10% to 75% of 2,3,3,3-tetrafluoropropene, from 5% to 60% of         1,1,1,2-tetrafluoroethane and from 20% to 80% of         3,3,3-trifluoropropene, preferably from 10% to 65% of         2,3,3,3-tetrafluoropropene, from 5% to 50% of         1,1,1,2-tetrafluoroethane and from 30% to 80% of         3,3,3-trifluoropropene; or     -   from 10% to 85% of 2,3,3,3-tetrafluoropropene, from 5% to 60% of         1,1,1,2-tetrafluoroethane and from 10% to 70% of         3,3,3-trifluoropropene, preferably from 10% to 60% of         2,3,3,3-tetrafluoropropene, from 5% to 50% of         1,1,1,2-tetrafluoroethane and from 20% to 60% of         3,3,3-trifluoropropene; or     -   from 15% to 67% of 2,3,3,3-tetrafluoropropene, from 3% to 10% of         1,1-difluoroethane and from 30% to 70% of         3,3,3-trifluoropropene, preferably from 21% to 57% of         2,3,3,3-tetrafluoropropene, from 3% to 9% of 1,1-difluoroethane         and from 40% to 70% of 3,3,3-trifluoropropene; or     -   from 35% to 89% of 2,3,3,3-tetrafluoropropene, from 3% to 15% of         1,1-difluoroethane and from 8% to 50% of 3,3,3-trifluoropropene,         preferably from 50% to 85% of 2,3,3,3-tetrafluoropropene, from         5% to 10% of 1,1-difluoroethane and from 10% to 40% of         3,3,3-trifluoropropene; or     -   from 15% to 50% of 1,3,3,3-tetrafluoropropene, from 35% to 82%         of 1,1,1,2-tetrafluoroethane and from 3% to 15% of         1,1-difluoroethane, preferably from 20% to 30% of         1,3,3,3-tetrafluoropropene, from 60% to 75% of         1,1,1,2-tetrafluoroethane and from 5% to 10% of         1,1-difluoroethane; or     -   from 10% to 40% of 1,3,3,3-tetrafluoropropene, from 45% to 87%         of 1,1,1,2-tetrafluoro ethane and from 3% to 15% of         1,1-difluoroethane, preferably from 10% to 30% of         1,3,3,3-tetrafluoropropene, from 60% to 85% of         1,1,1,2-tetrafluoroethane and from 5% to 10% of         1,1-difluoroethane; or     -   from 35% to 72% of 1,3,3,3-tetrafluoropropene, from 3% to 15% of         1,1-difluoroethane and from 25% to 50% of         3,3,3-trifluoropropene, preferably from 40% to 66% of         1,3,3,3-tetrafluoropropene, from 4% to 10% of 1,1-difluoroethane         and from 30% to 50% of 3,3,3-trifluoropropene; or     -   from 35% to 82% of 1,3,3,3-tetrafluoropropene, from 3% to 15% of         1,1-difluoroethane and from 15% to 50% of         3,3,3-trifluoropropene, preferably from 40% to 75% of         1,3,3,3-tetrafluoropropene, of 5% to 10% of 1,1-difluoroethane         and from 20% to 50% of 3,3,3-trifluoropropene.

According to one embodiment of any one of the above installations, the installation is a mobile or stationary air-conditioning installation, preferably a stationary air-conditioning installation.

Furthermore, one subject of the invention is a composition suitable for the implementation of any one of the above processes and suitable for the manufacture of any one of the above installations, comprising:

-   -   from 10% to 90% of 2,3,3,3-tetrafluoropropene, from 5% to 70% of         1,3,3,3-tetrafluoropropene and from 5% to 30% of         1,1-difluoroethane; or     -   from 5% to 90% of 2,3,3,3-tetrafluoropropene, from 5% to 60% of         1,1,1,2-tetrafluoroethane and from 5% to 80% of         3,3,3-trifluoropropene; or     -   from 10% to 89% of 2,3,3,3-tetrafluoropropene, from 3% to 20% of         1,1-difluoroethane and from 8% to 70% of 3,3,3-trifluoropropene.

According to one embodiment, the composition comprises:

-   -   from 20% to 85% of 2,3,3,3-tetrafluoropropene, from 5% to 50% of         1,3,3,3-tetrafluoropropene and from 10% to 30% of         1,1-difluoroethane, preferably from 35% to 80% of         2,3,3,3-tetrafluoropropene, from 5% to 40% of         1,3,3,3-tetrafluoropropene and from 15% to 25% of         1,1-difluoroethane; or     -   from 20% to 85% of 2,3,3,3-tetrafluoropropene, from 5% to 60% of         1,3,3,3-tetrafluoropropene and from 10% to 20% of         1,1-difluoroethane, preferably from 30% to 85% of         2,3,3,3-tetrafluoropropene, from 5% to 50% of         1,3,3,3-tetrafluoropropene, and from 10% to 15% of         1,1-difluoroethane; or     -   from 10% to 75% of 2,3,3,3-tetrafluoropropene, from 5% to 60% of         1,1,1,2-tetrafluoroethane and from 20% to 80% of         3,3,3-trifluoropropene, preferably from 10% to 65% of         2,3,3,3,-tetrafluoropropene, from 5% to 50% of         1,1,1,2-tetrafluoroethane and from 30% to 80% of         3,3,3-trifluoropropene; or     -   from 10% to 85% of 2,3,3,3-tetrafluoropropene, from 5% to 60% of         1,1,1,2-tetrafluoroethane and from 10% to 70% of         3,3,3-trifluoropropene, preferably from 10% to 60% of         2,3,3,3-tetrafluoropropene, from 5% to 50% of         1,1,1,2-tetrafluoroethane and from 20% to 60% of         3,3,3-trifluoropropene; or     -   from 15% to 67% of 2,3,3,3-tetrafluoropropene, from 3% to 10% of         1,1-difluoroethane and from 30% to 70% of         3,3,3-trifluoropropene, preferably from 21% to 57% of         2,3,3,3-tetrafluoropropene, from 3% to 9% of 1,1-difluoroethane         and from 40% to 70% of 3,3,3-trifluoropropene; or     -   from 35% to 89% of 2,3,3,3-tetrafluoropropene, from 3% to 15% of         1,1-difluoroethane and from 8% to 50% of 3,3,3-trifluoropropene,         preferably from 50% to 85% of 2,3,3,3-tetrafluoropropene, from         5% to 10% of 1,1-difluoroethane and from 10% to 40% of         3,3,3-trifluoropropene.

Another subject of the invention is a heat transfer composition, comprising the above composition, and also one or more additives chosen from lubricants, stabilizers, surfactants, tracers, fluorescent agents, odorous agents, solubilization agents and mixtures thereof.

The present invention makes it possible to overcome the drawbacks of the prior art. It provides, more particularly, heat transfer fluids suitable for replacing HFC-134a in a vapor compression system comprising a centrifugal compressor. The heat transfer fluids of the invention have a GWP below that of HFC-134a while guaranteeing a maintenance or even an improvement of the performances of the centrifugal compressor compared to HFC-134a. In particular, the invention makes any change of the compressor or of parts of the compressor unnecessary.

This is accomplished owing to the provision of mixtures of at least two compounds chosen from the following five compounds:

-   -   2,3,3,3-tetrafluoropropene (HFO-1234yf),     -   1,3,3,3-tetrafluoropropene (HFO-1234zc),     -   1,1,1,2-tetrafluoroethane (HFC-134a),     -   1,1-difluoroethane (HFC-152a) and     -   3,3,3-trifluoropropene (HFO-1243zf),         the proportions of these compounds being chosen such that:     -   1) the Mach number of the centrifugal compressor is virtually         identical to that of the centrifugal compressor operating with         pure HFC-134a, and     -   2) the compression ratio of the centrifugal compressor is less         than or equal to that of the centrifugal compressor operating         with pure HFC-134a.

This adjustment of the proportions of the various compounds as a function of the Mach number and of the compression ratio ensures that the performances of the vapor compression cycle are maintained relative to the operation with pure HFC-134a.

According to certain particular embodiments, the invention also has one or preferably more of the advantageous features listed below.

-   -   The proportions of the compounds of the mixture forming the heat         transfer fluid may also be adjusted so as to impose the         additional feature that the difference between the pressure at         the condenser and the pressure at the evaporator is lower (or         equal) when the heat transfer fluid is the mixture in question,         compared to the case where the heat transfer fluid is formed of         pure HFC-134a. This makes it possible to further improve the         operation of the centrifugal compressor.     -   Certain compositions proposed by the invention make it possible         to operate the centrifugal compressor at the same speed as when         pure HFC-134a is used as heat transfer fluid, the other         operating parameters being identical. These compositions are         particularly useful when the centrifugal compressor does not         comprise speed adaptation means, since they avoid having to         change the centrifugal compressor or parts thereof.     -   Certain compositions proposed by the invention make it possible         to operate the centrifugal compressor at a speed lower than that         obtained when pure HFC-134a is used as heat transfer fluid, the         other operating parameters being identical. These compositions         are particularly useful when the centrifugal compressor         comprises speed adaptation means, since they make it possible to         reduce the wear to which the centrifugal compressor is subjected         by decreasing the rotational speed.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The invention is now described in greater detail and non-limitingly in the description which follows.

Definitions and General Points

The proportions of all of the compounds are indicated in the application as weight percentages unless otherwise mentioned.

The invention firstly provides an installation comprising a vapor compression circuit containing a heat transfer fluid, and also a process for heating or cooling a fluid or a body which may be implemented by means of said installation.

The fluid or body heated or cooled may especially be air contained in an essentially closed space.

The vapor compression circuit containing a heat transfer fluid comprises at least an evaporator, a centrifugal compressor, a condenser and an expansion valve, and also lines for transporting heat transfer fluid between these components.

A centrifugal compressor is characterized in that it uses rotating components to radially accelerate the heat transfer fluid; it typically comprises at least a rotor and a diffuser housed in a chamber. The heat transfer fluid is introduced at the center of the rotor and flows toward the periphery of the rotor while undergoing an acceleration. Thus, on the one hand, the static pressure increases in the rotor, and above all, on the other hand, at the diffuser, the speed is converted to an increase in the static pressure. Each rotor/diffuser assembly constitutes one stage of the compressor. Centrifugal compressors may comprise from 1 to 12 stages, depending on the final pressure desired and the volume of fluid to be treated.

The compression ratio is defined as being the ratio of the absolute pressure of the heat transfer fluid at the outlet to the absolute pressure of said fluid at the inlet.

The rotational speed for large centrifugal compressors ranges from 3000 to 7000 rpm. Small centrifugal compressors (or mini centrifugal compressors) generally operate at a rotational speed which ranges from 40,000 to 70,000 rpm and comprise a rotor of small size (generally less than 0.15 m).

It is possible to use a multi-stage rotor to improve the efficiency of the compressor and limit the energy cost (compared to a single-stage rotor). For a two-stage system, the outlet of the first stage of the rotor feeds the inlet of the second rotor. The two rotors may be mounted on a single axis. Each stage may provide a compression ratio of the fluid of around 4 to 1, that is to say that the absolute outlet pressure may be equal to around four times the absolute suction pressure. Examples of two-stage centrifugal compressors, in particular for motor vehicle applications, are described in documents U.S. Pat. No. 5,065,990 and U.S. Pat. No. 5,363,674.

The centrifugal compressor may be driven by an electric motor or by a gas turbine (for example fed by the exhaust gases of a vehicle, for mobile applications) or by gearing.

The installation may comprise a coupling of the expansion valve with a turbine in order to produce electricity (Rankine cycle).

The installation may also optionally comprise at least one coolant circuit used for transmitting heat (with or without a change of state) between the heat transfer fluid circuit and the fluid or body to be heated or cooled.

The installation may also comprise two (or more) vapor compression circuits containing identical or different heat transfer fluids. For example, the vapor compression circuits may be coupled together.

The vapor compression circuit operates according to a conventional vapor compression cycle. The cycle comprises the change of state of the heat transfer fluid from a liquid phase (or liquid/vapor two phase state) to a vapor phase at a relatively low pressure, then the compression of the fluid in the vapor phase to a relatively high pressure, the change of state (condensation) of the heat transfer fluid from the vapor phase to the liquid phase at a relatively high pressure, and the reduction of the pressure in order to recommence the cycle.

In the case of a cooling process, heat from the fluid or from the body that is being cooled (directly or indirectly, via a coolant) is absorbed by the heat transfer fluid, during the evaporation of the latter, this being at a relatively low temperature compared to the surroundings.

In the case of a heating process, heat is imparted (directly or indirectly, via a coolant) from the heat transfer fluid, during the condensation thereof, to the fluid or body that is being heated, this being at a relatively high temperature compared to the surroundings.

The cooling or heating installation according to the invention may be a mobile or stationary installation.

It may especially be a heat pump installation, in which case the fluid or body that is being heated (generally air and optionally one or more products, articles or organisms) is located in a room or in a vehicle passenger compartment (for a mobile installation). According to one preferred embodiment, it is an air conditioning installation, in which case the fluid or body that is being cooled (generally air and optionally one or more products, articles or organisms) is located in a room or in a vehicle passenger compartment (for a mobile installation). It may be a refrigerating installation or a freezing installation (or cryogenic installation), in which case the fluid or body that is being cooled generally comprises air and one or more products, articles or organisms, located in a room or in a container.

The expressions “heat transfer compound”, respectively “heat transfer fluid” (or refrigerant fluid), are understood to mean a compound, respectively a fluid, capable of absorbing heat by evaporating at an evaporating temperature and evaporating pressure and of releasing heat by condensing at a condensing temperature and condensing pressure, which are greater, respectively, than the evaporating temperature and evaporating pressure, in a vapor compression circuit. A heat transfer fluid may comprise one, two, three or more than three heat transfer compounds.

One or more additives (which are predominantly not heat transfer compounds for the envisaged application) are generally added to the heat transfer fluid in order to provide a “heat transfer composition” that circulates in the vapor compression circuit.

The additives may especially be chosen from lubricants, stabilizers, surfactants, tracers, fluorescent agents, odorous agents and solubilization agents.

The stabilizer or stabilizers, when they are present, preferably represent at most 5% by weight in the heat transfer composition. Among the stabilizers, mention may especially be made of nitromethane, ascorbic acid, terephthalic acid, azoles such as tolutriazole or benzotriazole, phenolic compounds such as tocopherol, hydroquinone, t-butyl hydroquinone, 2,6-di-tert-butyl-4-methylphenol, epoxides (alkyl, optionally fluorinated or perfluorinated, or alkenyl or aromatic epoxides) such as n-butyl glycidyl ether, hexanediol diglycidyl ether, allyl glycidyl ether, butylphenyl glycidyl ether, phosphites, phosphonates, thiols and lactones.

As lubricants, use may especially be made of oils of mineral origin, silicone oils, paraffins of natural origin, naphthenes, synthetic paraffins, alkylbenzenes, poly-α-olefins, polyalkylene glycols, polyol esters and/or polyvinyl ethers.

As tracers (capable of being detected), mention may be made of deuterated or undeuterated hydrofluorocarbons, deuterated hydrocarbons, perfluorocarbons, fluoroethers, brominated compounds, iodinated compounds, alcohols, aldehydes, ketones, nitrogen protoxide and combinations thereof. The tracer is different from the heat transfer compound(s) making up the heat transfer fluid.

As solubilization agents, mention may be made of hydrocarbons, dimethyl ether, polyoxyalkylene ethers, amides, ketones, nitriles, chlorocarbons, esters, lactones, aryl ethers, fluoroethers and 1,1,1-trifluoroalkanes. The solubilization agent is different from the heat transfer compound(s) making up the heat transfer fluid.

As fluorescent agents, mention may be made of naphthalimides, perylenes, coumarins, anthracenes, phenanthracenes, xanthenes, thioxanthenes, naphthaxanthenes, fluoresceins and derivatives and combinations thereof.

As odorous agents, mention may be made of alkyl acrylates, allyl acrylates, acrylic acids, acrylic esters, alkyl ethers, alkyl esters, alkynes, aldehydes, thiols, thioethers, disulfides, allyl isothiocyanates, alkanoic acids, amines, norbornenes, derivatives of norbornenes, cyclohexene, heterocyclic aromatic compounds, ascaridole, o-methoxy(methyl)phenol and combinations thereof.

According to the present application, the global warming potential (GWP) is defined relative to carbon dioxide and relative to a period of 100 years, according to the method indicated in “The scientific assessment of ozone depletion, 2002, a report of the World Meteorological Association's Global Ozone Research and Monitoring Project”.

Implementation of the Invention

The invention is based on the choice of two criteria that make it possible to produce heat transfer fluids suitable for vapor compression circuits comprising a centrifugal compressor, and more specifically that make it possible to maintain (or improve) the performances of the centrifugal compressor without having to modify the structure thereof, relative to an operation based on the use of pure HFC-134a as heat transfer fluid.

The first criterion set by the invention is that of the Mach number. The Mach number is equal to the ratio of the peripheral speed of the rotor of the compressor to the speed of sound at the inlet of said rotor.

The second criterion set by the invention is that of the compression ratio of this compressor. The compression ratio is the ratio of the absolute pressure at the outlet to the absolute pressure at the inlet of the centrifugal compressor.

In order to guarantee that the performances of the centrifugal compressor are maintained (or even improved) relative to the heat transfer fluid HFC-134a, it is desired for the Mach number M₂ of the centrifugal compressor operating with the heat transfer fluid in question to be practically equal to the reference Mach number M₁ of the centrifugal compressor operating with pure HFC-134a as heat transfer fluid; more specifically, it is desired for the M₂/M₁ ratio to be greater than or equal to 0.97 and less than or equal to 1.03 (preferably greater than or equal to 0.98 and less than or equal to 1.02, or greater than or equal to 0.99 and less than or equal to 1.01, or equal to approximately 1); and it is also desired for the compression ratio T₂ of the centrifugal compressor operating with the heat transfer fluid in question to be less than or equal to the reference compression ratio T₁ of the centrifugal compressor operating with pure HFC-134a as heat transfer fluid.

A third criterion (optionally) used according to the invention, in addition to the preceding two, is that of the difference between the pressure at the condenser and the pressure at the evaporator. Thus, according to one particular embodiment, it is desired for this pressure difference DP₂ of the vapor compression circuit operating with the heat transfer fluid in question to be less than or equal to the pressure difference DP₁ of the vapor compression circuit operating with the reference heat transfer fluid (pure HFC-134a).

The Mach number of the centrifugal compressor must be virtually identical to that of the centrifugal compressor operating with pure HFC-134a in order to guarantee an equivalent operation and to enable a possible conversion of the installation. On the other hand, at constant rotational speed, the increase of the compression ratio results in a decrease of the power of the compressor working under the same temperature conditions. Similarly, the work necessary for the compression decreases with the decrease of the pressure difference between the evaporator and the condenser. This means that the efficiency of the system increases with the decrease of the pressure difference and of the compression ratio between the evaporator and the condenser for the same operating temperatures.

For each of the preceding criteria, the comparison between the heat transfer fluid in question and pure HFC-134a is carried out under the same operating conditions, which means, on the one hand, that the vapor compression circuit is exactly the same and the structure of the centrifugal compressor is exactly the same; and, on the other hand, that the temperature at the evaporator and at the condenser are identical in both cases. For example, the comparison may be made with a temperature of 4° C. at the evaporator and of 37° C. at the condenser.

According to the second variant of the invention (constant speed variant), the centrifugal compressor operates at a predetermined speed which cannot be modified. The rotor then rotates at the same speed with the transfer fluid in question and with the reference fluid (pure HFC-134a).

On the other hand, according to the first variant of the invention (variable speed variant), the centrifugal compressor may operate in a certain range of speeds. This is especially the case for a centrifugal compressor operating with an electric motor and endowed with a variable speed drive.

In this first variant, a modification of the speed of the compressor between the operation with the reference heat transfer fluid (pure HFC-134a) and the transfer fluid in question may make it possible to obtain an M₂/M₁ ratio from 0.97 to 1.03 and a T₂/T₁ ratio less than or equal to 1 for heat transfer fluid formulations other than those that make it possible to obtain an M₂/M₁ ratio from 0.97 to 1.03 and a T₂/T₁ ratio less than or equal to 1 at identical rotor speed. In other words, this second embodiment makes it possible to broaden the range of heat transfer fluids that can be envisaged.

Still according to this first variant, it is particularly advantageous to make provision for the speed of the rotor with the heat transfer fluid in question to be less than the speed of the rotor with the reference heat transfer fluid (pure HFC-134a). Indeed, this makes it possible to limit the wear to which the centrifugal compressor is subjected.

In both variants, the M₂/M₁ and T₂/T₁ (and optionally DP₂/DP₁) ratios may be determined experimentally or by calculation and/or numerical simulation.

The Mach number, the compression ratio and the pressure difference are calculated for each mixture under the same typical operating conditions. These calculations are performed using the corresponding thermodynamic models for each product. The modeling method is based on the RK-Soave equation. The development of the models is based on experimental measurements described in example 1.

Heat transfer fluids comprising at least two compounds chosen from HFO-1234yf, HFO-1234ze, HFC-134a, HFC-152a and HFO-1243zf satisfy the two (or three) criteria mentioned above and therefore provide very effective substitutes for pure HFC-134a in the vapor compression circuits with a centrifugal compressor.

All of these five compounds have a similar boiling point, between −30 and −18° C.

HFO-1234ze can be in its cis or trans form. Preferably, the HFO-1234ze used within the context of the invention contains at least 80% of trans form, preferably at least 90% or at least 95% or at least 98% or at least 99% of trans form.

These heat transfer fluids may be constituted by two of the above compounds or three of the above compounds or four of the above compounds or else the five compounds above.

In addition, it is desirable for the heat transfer fluids:

-   -   to be nonflammable (within the meaning of the ASHRAE 34-2007         standard, and preferably with a test temperature of 60° C.         instead of 100° C.);     -   to be quasi-azeotropic; and     -   to have a low GWP (in particular, the heat transfer fluids may         have a GWP less than or equal to 1250, preferably less than or         equal to 1000, less than or equal to 750, less than or equal to         500, less than or equal to 250, or less than or equal to 150).

Heat transfer fluids that are particularly suitable for the substitution of pure HFC-134a in a vapor compression circuit comprising a constant speed centrifugal compressor are listed below:

-   -   binary heat transfer fluids:         -   HFO-1234y/HFC-134a: from 2 to 50% of HFO-1234yf and from 50             to 98% of HFC-134a, in particular from 2 to 30% of             HFO-1234yf and from 70 to 98% of HFC-134a, and in particular             from 5 to 15% of HFO-1234yf and from 85 to 95% of HFC-134a;         -   HFO-1234yf/HFC-152a: from 50 to 90% of HFO-1234yf and from             10 to 50% of HFC-152a, in particular from 60 to 90% of             HFO-1234yf and from 10 to 40% of HFC-152a and in particular             from 70 to 80% of HFO-1234yf and from 20 to 30% of HFC-152a;         -   HFO-1243zf/HFC-134a: from 30 to 90% of HFO-1243zf and from             10 to 70% of HFC-134a, in particular from 40 to 80% of             HFO-1243zf and from 20 to 60% of HFC-134a, and in particular             from 50 to 65% of HFO-1243zf and from 35 to 50% of HFC-134a;         -   HFO-1243zf/HFO-1234yf: from 60 to 90% of HFO-1243zf and from             10 to 40% of HFO-1234yf, in particular from 70 to 90% of             HFO-1243zf and from 10 to 30% of HFO-1234yf, and in             particular from 80 to 90% of HFO-1243zf and from 10 to 20%             of HFO-1234yf;         -   HFO-1243zf/HFO-1234ze: from 30 to 80% of HFO-1243zf and from             20 to 70% of HFO-1234ze, in particular from 40 to 70% of             HFO-1243zf and from 20 to 60% of HFO-1234ze, and in             particular from 50 to 70% of HFO-1243zf and from 30 to 50%             of HFO-1234ze;     -   ternary heat transfer fluids:         -   HFO-1234yf/HFC-134a/HFC-152a: from 18 to 93% of HFO-1234yf             and from 5 to 80% of HFC-134a and from 2 to 50% of HFC-152a,             in particular from 20 to 93% of HFO-1234yf and from 5 to 60%             of HFC-134a and from 2 to 30% of HFC-152a, and in particular             from 30 to 88% of HFO-1234yf and from 5 to 60% of HFC-134a             and from 7 to 20% of HFC-152a;         -   HFO-1234yf/HFC-134a/HFO-1243zf: from 10 to 80% of HFO-1234yf             and from 5 to 60% of HFC-134a and from 15 to 80% of             HFO-1243zf, in particular from 10 to 75% of HFO-1234yf and             from 5 to 60% of HFC-134a and from 20 to 80% of HFO-1243zf,             and in particular from 10 to 65% of HFO-1234yf and from 5 to             50% of HFC-134a and from 30 to 80% of HFO-1243zf;         -   HFO-1234yf/HFC-152a/HFO-1234ze: from 15 to 85% of HFO-1234yf             and from 5 to 30% of HFC-152a and from 5 to 60% of             HFO-1234ze, in particular from 20 to 85% of HFO-1234yf and             from 10 to 30% of HFC-152a and from 5 to 50% of HFO-1234ze,             and in particular from 35 to 80% of HFO-1234yf and from 15             to 25% of HFC-152a and from 5 to 40% of HFO-1234ze;         -   HFO-1234yf/HFC-152a/HFO-1243zf: from 10 to 78% of HFO-1234yf             and from 3 to 15% of HFC-152a and from 20 to 70% of             HFO-1243zf, in particular from 15 to 67% of HFO-1234yf and             from 3 to 10% of HFC-152a and from 30 to 70% of HFO-1243zf,             and in particular from 21 to 57% of HFO-1234yf and from 3 to             9% of HFC-152a and from 40 to 70% of HFO-1243zf;         -   HFC-134a/HFC-152a/HFO-1234ze: from 20 to 82% of HFC-134a and             from 3 to 20% of HFC-152a and from 15 to 60% of HFO-1234ze,             in particular from 35 to 82% of HFC-134a and from 3 to 15%             of HFC-152a and from 15 to 50% of HFO-1234ze, and in             particular from 60 to 75% of HFC-134a and from 5 to 10% of             HFC-152a and from 20 to 30% of HFO-1234ze;         -   HFC-152a/HFO-1243zf/HFO-1234ze: from 3 to 15% of HFO-152a             and from 20 to 50% of HFO-1243zf and from 35 to 77% of             HFO-1234ze, in particular from 3 to 15% of HFO-152a and from             25 to 50% of HFO-1243zf and from 35 to 72% of HFO-1234ze,             and in particular from 4 to 10% of HFO-152a and from 30 to             50% of HFO-1243zf and from 40 to 66% of HFO-1234ze.

Heat transfer fluids that are particularly suitable for the substitution of pure HFC-134a in a vapor compression circuit comprising a variable speed centrifugal compressor, and in particular that enable operation of the centrifugal compressor at lower speed relative to operation with pure HFC-134a are listed below:

-   -   binary heat transfer fluids:         -   HFO-1234yf/HFC-134a: from 2 to 50% of HFO-1234yf and from 50             to 98% of HFC-134a, in particular from 5 to 40% of             HFO-1234yf and from 60 to 95% of HFC-134a, and in particular             from 5 to 30% of HFO-1234yf and from 70 to 95% of HFC-134a;         -   HFO-1234yf/HFC-152a: from 50 to 95% of HFO-1234yf and from 5             to 50% of HFC-152a, in particular from 60 to 95% of             HFO-1234yf and from 5 to 40% of HFC-152a, and in particular             from 85 to 90% of HFO-1234yf and from 10 to 15% of HFC-152a;         -   HFO-1243zf/HFC-134a: from 30 to 90% of HFO-1243zf and from             10 to 70% of HFC-134a, in particular from 40 to 80% of             HFO-1243zf and from 20 to 60% of HFC-134a, and in particular             from 50 to 65% of HFO-1243zf and from 35 to 50% of HFC-134a;         -   HFO-1243zf/HFO-1234yf: from 30 to 90% of HFO-1243zf and from             10 to 70% of HFO-1234yf, in particular from 40 to 80% of             HFO-1243zf and from 20 to 60% of HFO-1234yf, and in             particular from 50 to 60% of HFO-1243zf and from 40 to 50%             of HFO-1234yf;         -   HFO-1243zf/HFO-1234ze: from 30 to 80% of HFO-1243zf and from             20 to 70% of HFO-1234ze, in particular from 40 to 70% of             HFO-1243zf and from 30 to 60% of HFO-1234ze, and in             particular from 50 to 70% of HFO-1243zf and from 30 to 50%             of HFO-1234ze;     -   ternary heat transfer fluids:         -   HFO-1234yf/HFC-134a/HFC-152a: from 10 to 93% of HFO-1234yf             and from 5 to 80% of HFC-134a and from 2 to 50% of HFC-152a,             in particular from 13 to 93% of HFO-1234yf and from 5 to 60%             of HFC-134a and from 2 to 30% of HFC-152a, and in particular             from 25 to 92% of HFO-1234yf and from 5 to 60% of HFC-134a             and from 3 to 15% of HFC-152a;         -   HFO-1234yf/HFC-134a/HFO-1243zf: from 5 to 90% of HFO-1234yf             and from 5 to 60% of HFC-134a and from 5 to 70% of             HFO-1243zf, in particular from 10 to 85% of HFO-1234yf and             from 5 to 60% of HFO-134a and from 10 to 70% of HFC-1243zf,             and in particular from 10 to 60% of HFO-1234yf and from 5 to             50% of HFC-134a and from 20 to 60% of HFO-1243zf;         -   HFO-1234yf/HFC-152a/HFO-1234ze: from 10 to 90% of HFO-1234yf             and from 5 to 30% of HFC-152a and from 5 to 70% of             HFO-1234ze, in particular from 20 to 85% of HFO-1234yf and             from 10 to 20% of HFC-152a and from 5 to 60% of HFO-1234ze,             and in particular from 30 to 85% of HFO-1234yf and from 10             to 15% of HFC-152a and from 5 to 50% of HFO-1234ze;         -   HFO-1234yf/HFC-152a/HFO-1243zf: from 10 to 89% of HFO-1234yf             and from 3 to 20% of HFC-152a and from 8 to 70% of             HFO-1243zf, in particular from 35 to 89% of HFO-1234yf and             from 3 to 15% of HFC-152a and from 8 to 50% of HFO-1243zf,             and in particular from 50 to 85% of HFO-1234yf and from 5 to             10% of HFC-152a and from 10 to 40% of HFO-1243zf;         -   HFC-134a/HFC-152a/HFO-1234ze: from 20 to 87% of HFC-134a and             from 3 to 20% of HFC-152a and from 10 to 60% of HFO-1234ze,             in particular from 45 to 87% of HFC-134a and from 3 to 15%             of HFC-152a and from 10 to 40% of HFO-1234ze, and in             particular from 60 to 85% of HFC-134a and from 5 to 10% of             HFC-152a and from 10 to 30% of HFO-1234ze;         -   HFC-152a/HFO-1243zf/HFO-1234ze: from 3 to 15% of HFO-152a             and from 15 to 60% of HFO-1243zf and from 25 to 82% of             HFO-1234ze, in particular from 3 to 15% of HFO-152a and from             15 to 50% of HFO-1243zf and from 35 to 82% of HFO-1234ze,             and in particular from 5 to 10% of HFO-152a and from 20 to             50% of HFO-1243zf and from 40 to 75% of HFO-1234ze.

EXAMPLES

The following examples illustrate the invention without limiting it.

Example 1 Centrifugal Compressor Operating at Constant Speed

In this example, a vapor compression circuit equipped with an evaporator, a condenser, a single-stage centrifugal compressor and an expansion valve is considered. The system operates with 0° C. of superheating, 0° C. of subcooling, an evaporating temperature of the heat transfer fluid at the evaporator of 4° C. and a condensing temperature of the heat transfer fluid at the condenser of 37° C.

The performances of the system with various heat transfer fluids are calculated. In order to do this, the RK-Soave equation is used for determining the specific densities, enthalpies, entropies, speed of sound, temperature, pressure and heat.

The data relating to each pure body necessary for the calculation are firstly the boiling point, the critical temperature and pressure, the pressure curve as a function of temperature from the boiling point to the critical point, the saturated liquid and saturated vapor densities as a function of the temperature, the specific heat of the ideal gases, this being for each pure body.

For HFC-134a and HFC-152a, the data is published in the ASHRAE Handbook 2005, chapter 20 and are also available in the Refprop software from NIST.

For HFO-1234ze, HFO-1234yf and HFO-1243zf, the temperature/pressure curve is measured by the static method. The critical temperature and the critical pressure are measured by a C80 calorimeter sold by Setaram. The saturation densities as a function of the temperature are measured by the technology of the vibrating-tube densimeter (laboratories of the Ecole des Mines de Paris).

Also used as data in the calculations are the binary mixture interaction coefficients, in order to represent the behavior of the products as mixtures. The coefficients are calculated as a function of the experimental liquid/vapor equilibrium data.

The technique used for the liquid/vapor equilibrium measurements is the static cell analytical method. The equilibrium cell comprises a sapphire tube and is equipped with two electromagnetic ROLSITM samplers. It is immersed in a cryothermostat bath (HUBER HS40). A magnetic stirrer with field drive rotating at variable speed is used to accelerate the attaining of the equilibria. The analysis of the samples is carried out by gas chromatography (HP5890 series II) using a katharometer (TCD).

The liquid/vapor equilibrium measurements on the HFC-134a/HFO-1234yf binary mixture are carried out for the isotherm of 20° C. The liquid/vapor equilibrium measurements on the HFO-1234yf/HFC-152a binary mixture are carried out for the isotherm of 10° C. The liquid/vapor equilibrium measurements on the HFO-1234ze/HFC-152a binary mixture are carried out for the isotherm of 15° C. The liquid/vapor equilibrium measurements on the HFC-134a/HFO-1234ze binary mixture are carried out for the isotherm of 20° C. The liquid/vapor equilibrium measurements on the HFO-1234ze/HFO-1234yf binary mixture are carried out for the isotherm of 18° C. The liquid/vapor equilibrium measurements on the HFO-1243zf/HFO-1234yf binary mixture are carried out for the isotherm of 21° C. The liquid/vapor equilibrium measurements on the HFO-1243zf/HFC-152a binary mixture are carried out for the isotherm of 10° C. The liquid/vapor equilibrium measurements on the HFO-1243zf/HFC-134a binary mixture are carried out for the isotherm of 10° C.

The liquid/vapor equilibrium data for the HFC-134a/HFC-152a binary mixture are available from Refprop. Four isotherms (−10, 30, 40 and 50° C.) and two isobars (1 bar and 30 bar) are used for the calculation of the interaction coefficients for this binary mixture.

In the present example, it is considered that the centrifugal compressor operates at constant speed. Tables 1a, 1b and 1c summarize the performances obtained with a few heat transfer fluids according to the invention, in comparison with pure HFC-134a.

TABLE 1a performances obtained with a few binary mixtures according to the invention Speed of Evaporator Condenser Pressure Compres- sound at Molec- Mach HFC-134a pressure pressure difference sion compressor Glide ular % M/M HFO- HFC- HFC- HFO- HFO- (bar) (bar) (bar) ratio inlet (m/s) (° C.) weight (HFC-134a) 1234yf 134a 152a 1243zf 1234ze 3.4 9.4 6.0 2.8 148 0.0 102 100 15 85 0 0 0 3.5 9.5 6.1 2.7 146 0.1 104 101 5 95 0 0 0 3.4 9.4 6.0 2.8 148 0.1 103 100 80 0 20 0 0 3.6 9.3 5.7 2.6 148 0.0 104 101 70 0 30 0 0 3.6 9.3 5.7 2.6 153 0.1 100 97 0 40 0 60 0 3.3 9.2 5.9 2.8 150 0.1 98 99 20 0 0 80 0 3.2 8.4 5.2 2.6 149 0.1 100 100 10 0 0 90 0 3.2 8.3 5.1 2.6 151 0.1 98 99

TABLE 1b performances obtained with a few ternary mixtures according to the invention Speed of Evaporator Condenser Pressure Compres- sound at Molec- Mach HFC-134a pressure pressure difference sion compressor Glide ular % M/M HFO- HFC- HFC- HFO- HFO- (bar) (bar) (bar) ratio inlet (m/s) (° C.) weight (HFC-134a) 1234yf 134a 152a 1243zf 1234ze 3.4 9.4 6.0 2.8 148 0.0 102 100 75 5 20 0 0 3.6 9.3 5.7 2.6 148 0.0 104 100 70 10 20 0 0 3.6 9.4 5.7 2.6 149 0.0 103 100 65 20 15 0 0 3.6 9.4 5.8 2.6 147 0.0 104 101 60 20 20 0 0 3.6 9.4 5.8 2.6 150 0.1 102 99 55 30 15 0 0 3.6 9.5 5.8 2.6 148 0.1 103 100 40 50 10 0 0 3.6 9.5 5.9 2.7 148 0.1 103 100 38 50 12 0 0 3.6 9.5 5.9 2.7 149 0.2 102 100 33 60 7 0 0 3.6 9.6 6.0 2.7 147 0.2 103 101 30 60 10 0 0 3.5 9.5 6.0 2.7 149 0.2 102 100 35 5 0 60 0 3.3 8.7 5.4 2.6 146 0.1 103 101 25 5 0 70 0 3.3 8.6 5.4 2.7 148 0.1 101 100 15 5 0 80 0 3.2 8.5 5.3 2.7 150 0.1 99 99 30 10 0 60 0 3.3 8.8 5.5 2.7 147 0.1 102 101 20 10 0 70 0 3.3 8.7 5.5 2.7 149 0.1 100 100 30 20 0 50 0 3.4 9.1 5.7 2.7 147 0.1 103 101 20 20 0 60 0 3.3 9.0 5.7 2.7 148 0.1 101 100 10 20 0 70 0 3.3 8.9 5.6 2.7 150 0.1 99 99 20 30 0 50 0 3.4 9.2 5.8 2.7 148 0.1 101 100 10 30 0 60 0 3.3 9.1 5.8 2.7 149 0.1 100 99 20 50 0 30 0 3.5 9.5 6.0 2.7 147 0.1 103 101 10 50 0 40 0 3.4 9.4 6.0 2.8 148 0.1 101 100

TABLE 1c performances obtained with a few ternary mixtures according to the invention Speed of Evaporator Condenser Pressure Compres- sound at Molec- Mach HFC-134a pressure pressure difference sion compressor Glide ular % M/M HFO- HFC- HFC- HFO- HFO- (bar) (bar) (bar) ratio inlet (m/s) (° C.) weight (HFC-134a) 1234yf 134a 152a 1243zf 1234ze 3.4 9.4 6.0 2.8 148 0.0 102 100 75 0 20 0 5 3.6 9.3 5.7 2.6 148 0.1 104 100 70 0 20 0 10 3.5 9.2 5.7 2.6 148 0.2 104 100 65 0 20 0 15 3.5 9.1 5.7 2.6 148 0.2 104 100 60 0 20 0 20 3.4 9.1 5.7 2.7 148 0.3 104 100 50 0 20 0 30 3.3 8.9 5.6 2.7 149 0.5 104 100 40 0 20 0 40 3.2 8.7 5.5 2.8 149 0.6 104 99 45 0 5 50 0 3.3 8.8 5.5 2.6 147 0.1 103 101 35 0 5 60 0 3.3 8.7 5.4 2.6 149 0.1 101 100 25 0 5 70 0 3.2 8.6 5.3 2.6 150 0.1 99 99 53 0 7 40 0 3.4 8.9 5.5 2.6 147 0.1 103 101 43 0 7 50 0 3.3 8.8 5.5 2.6 148 0.1 102 100 33 0 7 60 0 3.3 8.7 5.4 2.6 150 0.1 100 99 0 75 5 0 20 3.2 9.0 5.8 2.8 149 0.1 103 100 0 60 10 0 30 3.1 8.8 5.7 2.8 150 0.2 102 99

Example 2 Centrifugal Compressor Operating at Variable Speed

In this example, the same calculations as in example 1 are reproduced, but by considering that the speed of the centrifugal compressor may be adapted relative to the rotational speed with HFC-134a. Tables 2a, 2b and 2c summarize the performances obtained with a few heat transfer fluids according to the invention, in comparison with pure HFC-134a.

TABLE 2a performances obtained with a few binary mixtures according to the invention Mach Speed of (speed Evaporator Condenser Pressure Compres- sound at Molec- adjustment % speed/ HFC-134a pressure pressure difference sion compressor Glide ular % M/M speed HFO- HFC- HFC- HFO- HFO- (bar) (bar) (bar) ratio inlet (m/s) (° C.) weight (HFC-134a) HFC-134a 1234yf 134a 152a 1243zf 1234ze 3.4 9.4 6.0 2.8 148 0.0 102 100 100 30 70 0 0 0 3.6 9.7 6.1 2.7 144 0.1 106 101 98 15 85 0 0 0 3.5 9.5 6.1 2.7 146 0.1 104 101 99 5 95 0 0 0 3.4 9.4 6.0 2.8 148 0.1 103 100 100 90 0 10 0 0 3.6 9.4 5.7 2.6 142 0.0 109 101 97 85 0 15 0 0 3.6 9.3 5.7 2.6 145 0.0 107 99 97 0 40 0 60 0 3.3 9.2 5.9 2.8 150 0.1 98 99 100 50 0 0 50 0 3.3 8.8 5.4 2.6 144 0.1 105 100 97 40 0 0 60 0 3.3 8.6 5.4 2.6 146 0.1 103 99 97

TABLE 2b performances obtained with a few ternary mixtures according to the invention Mach Speed of (speed Evaporator Condenser Pressure Compres- sound at Molec- adjustment % speed/ HFC-134a pressure pressure difference sion compressor Glide ular % M/M speed HFO- HFC- HFC- HFO- HFO- (bar) (bar) (bar) ratio inlet (m/s) (° C.) weight (HFC-134a) HFC-134a 1234yf 134a 152a 1243zf 1234ze 3.4 9.4 6.0 2.8 148 0.0 102 100 100 85 5 10 0 0 3.6 9.4 5.8 2.6 143 0.0 109 101 93 80 5 15 0 0 3.6 9.4 5.7 2.6 145 0.0 106 99 93 80 10 10 0 0 3.6 9.4 5.8 2.6 143 0.0 108 100 94 78 10 12 0 0 3.6 9.4 5.8 2.6 144 0.0 107 99 94 73 20 7 0 0 3.7 9.5 5.8 2.6 142 0.0 108 101 94 72 20 8 0 0 3.7 9.5 5.8 2.6 143 0.0 108 100 94 70 20 10 0 0 3.7 9.5 5.8 2.6 144 0.0 107 100 94 65 30 5 0 0 3.7 9.6 5.9 2.6 142 0.0 108 101 94 63 30 7 0 0 3.7 9.6 5.9 2.6 144 0.0 107 100 94 62 30 8 0 0 3.7 9.5 5.9 2.6 144 0.0 107 100 94 60 30 10 0 0 3.6 9.5 5.9 2.6 145 0.0 106 99 94 45 50 5 0 0 3.6 9.6 6.0 2.6 145 0.1 106 100 96 37 60 3 0 0 3.6 9.6 6.0 2.7 145 0.1 105 101 96 35 60 5 0 0 3.6 9.6 6.0 2.7 146 0.2 104 100 97 33 60 7 0 0 3.6 9.6 6.0 2.7 147 0.2 103 99 97 55 5 0 40 0 3.4 9.0 5.6 2.6 143 0.1 106 101 95 45 5 0 50 0 3.3 8.8 5.5 2.6 145 0.1 104 100 96 35 5 0 60 0 3.3 8.7 5.4 2.6 146 0.1 103 99 96 50 10 0 40 0 3.4 9.0 5.6 2.7 144 0.1 106 101 96 40 10 0 50 0 3.4 8.9 5.6 2.7 145 0.1 104 100 96 30 10 0 60 0 3.3 8.8 5.5 2.7 147 0.1 102 99 96 40 20 0 40 0 3.4 9.2 5.8 2.7 145 0.1 104 101 97 30 20 0 50 0 3.4 9.1 5.7 2.7 147 0.1 103 100 97 20 20 0 60 0 3.3 9.0 5.7 2.7 148 0.1 101 99 98 40 30 0 30 0 3.5 9.4 5.9 2.7 145 0.1 105 101 97 30 30 0 40 0 3.4 9.3 5.9 2.7 146 0.1 103 101 98 20 30 0 50 0 3.4 9.2 5.8 2.7 148 0.1 101 100 99 10 30 0 60 0 3.3 9.1 5.8 2.7 149 0.1 100 99 99 30 50 0 20 0 3.5 9.6 6.0 2.7 145 0.1 104 101 98 20 50 0 30 0 3.5 9.5 6.0 2.7 147 0.1 103 101 99 10 50 0 40 0 3.4 9.4 6.0 2.8 148 0.1 101 100 100

TABLE 2c performances obtained with a few ternary mixtures according to the invention Mach Speed of (speed Evaporator Condenser Pressure Compres- sound at Molec- adjustment % speed/ HFC-134a pressure pressure difference sion compressor Glide ular % M/M speed HFO- HFC- HFC- HFO- HFO- (bar) (bar) (bar) ratio inlet (m/s) (° C.) weight (HFC-134a) HFC-134a 1234yf 134a 152a 1243zf 1234ze 3.4 9.4 6.0 2.8 148 0.0 102 100 100 83 0 12 0 5 3.6 9.3 5.7 2.6 143 0.1 108 100 94 78 0 12 0 10 3.5 9.2 5.7 2.6 144 0.1 108 101 95 65 0 15 0 20 3.4 9.1 5.7 2.7 146 0.3 107 100 96 55 0 15 0 30 3.3 8.9 5.6 2.7 146 0.5 107 100 98 45 0 15 0 40 3.2 8.7 5.6 2.7 146 0.6 107 101 99 50 0 20 0 30 3.3 8.9 5.6 2.7 149 0.5 104 99 98 40 0 20 0 40 3.2 8.7 5.5 2.8 149 0.6 104 99 99 30 0 20 0 50 3.0 8.5 5.4 2.8 150 0.7 104 99 101 75 0 5 20 0 3.5 9.1 5.7 2.6 142 0.1 108 101 94 65 0 5 30 0 3.4 9.0 5.6 2.6 144 0.1 106 100 95 60 0 5 35 0 3.4 9.0 5.6 2.6 145 0.1 105 100 95 55 0 5 40 0 3.4 8.9 5.5 2.6 146 0.1 104 99 95 83 0 7 10 0 3.6 9.2 5.7 2.6 142 0.0 109 101 94 73 0 7 20 0 3.5 9.2 5.7 2.6 144 0.1 107 100 94 63 0 7 30 0 3.4 9.0 5.6 2.6 145 0.1 105 99 95 53 0 7 40 0 3.4 8.9 5.5 2.6 147 0.1 103 99 95 

The invention claimed is:
 1. A process for converting a vapor compression circuit comprising a centrifugal compressor containing 1,1,1,2-tetrafluoroethane as heat transfer fluid comprising: removing said 1,1,1,2-tetrafluoroethane from said vapor compression circuit; and adding a substitute heat transfer fluid comprising at least two compounds selected from a group consisting of 2,3,3,3-tetrafluoropropene, 1,3,3,3-tetrafluoropropene, 1,1,1,2-tetrafluoroethane, and 1,1-difluoroethane, and wherein: a ratio of the Mach number of the centrifugal compressor containing said substitute heat transfer fluid to the Mach number of the centrifugal compressor containing said 1,1,1,2-tetrafluoroethane, under the same operating conditions, is greater than or equal to 0.97 and less than or equal to 1.03; and a compression ratio of the centrifugal compressor containing said substitute heat transfer fluid is less than or equal to the compression ratio of the centrifugal compressor containing said 1,1,1,2-tetrafluoroethane, under the same operating conditions, wherein the centrifugal compressor is provided with rotational speed adaptation means, and wherein: a rotational speed of the centrifugal compressor in the vapor compression circuit containing said substitute heat transfer fluid is adjusted to a value less than or equal to the rotational speed of the centrifugal compressor in the vapor compression circuit containing said 1,1,1,2-tetrafluoroethane, under the same operating conditions.
 2. The process as claimed in claim 1, wherein the substitute heat transfer fluid comprises, a mixture selected from the group consisting of: 2,3,3,3-tetrafluoropropene and 1,1,1,2-tetrafluoroethane; 2,3,3,3-tetrafluoropropene, 1,1,1,2-tetrafluoroethane and 1,1-difluoroethane; and 1,3,3,3-tetrafluoropropene, 1,1,1,2-tetrafluoroethane and 1,1-difluoroethane.
 3. The process as claimed in claim 1, wherein the vapor compression circuit comprises an evaporator and a condenser, and wherein: a difference between the pressure at the condenser and the pressure at the evaporator in the vapor compression circuit containing said substitute heat transfer fluid is less than or equal to the difference between the pressure at the condenser and the pressure at the evaporator in the vapor compression circuit containing said 1,1,1,2-tetrafluoroethane, under the same operating conditions.
 4. The process as claimed in claim 1, wherein the substitute heat transfer fluid comprises a mixture selected from the group consisting of: from 2% to 50% of 2,3,3,3-tetrafluoropropene and from 50% to 98% of 1,1,1,2-tetrafluoroethane; from 10% to 93% of 2,3,3,3-tetrafluoropropene, from 5% to 80% of 1,1,1,2-tetrafluoroethane and from 2% to 50% of 1,1-difluoroethane; and from 10% to 60% of 1,3,3,3-tetrafluoropropene, from 20% to 87% of 1,1,1,2-tetrafluoroethane and from 3% to 20% of 1,1-difluoroethane. 